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Choosing a Grinder/Polisher

We have a wide variety of grinding and polishing machines for working with both glass and stones. If you are a glass artist we suggest a glass lathe style unit as they have more reach for working large pieces. Our stone grinders come in a wide variety of styles and options to suit many different needs.

Expandable Drum Units

Covington has 2 different machines that come with expandable drums included. Expandable drums are soft wheels that expand when they spin. They are used with either silicon carbide or diamond sanding belts. The belts easily slide onto the wheel when the wheel is stationary and then lock into place when the wheel is spinning.

Expandable drums are a great choice for contouring your rocks. Their soft surface flexes under your touch which makes smoothing of cabochons and other domed shapes easy.

Covington has an economical 2-station machine as well as a 4-station machine which allows you to go through all of the pre-polish grinding stages without changing wheels or machines. You can also set up your expandable drum machine with polishing belts such as cork and felt for glass or fine diamond belts for stone.

Customizable Grinder/Polishers

We also has several more versatile grinding unit options. Two Covington machines do not come with wheels attached, which gives the user the freedom to customize the machine to their exact needs.

The Heavy Duty Grinder/Polisher and Variable Speed Grinder are both 2-station arbor units that can accommodate 6” and 8” grinding and polishing wheels. Wheel options range from silicon carbide stone wheels to diamond-plated and sintered wheels, to cork and felt wheels. The Variable Speed Grinder allows you to control how fast or slow you need the wheels to turn. Both units are pulley driven, which allows for a truer-running shaft and reduced vibration on the wheels.

Complete Grinder/Polishers

Complete Grinder/Polisher machines allow you to fully grind and polish pieces on one machine without changing out wheels. These machines are perfect for you if you already have your pieces slabbed and are simply going to finish your pieces by grinding, shaping, and polishing.

Covington has an 8" Grinder/Polisher that comes with 2 hard wheels (either silicon carbide or diamond), an expandable drum, and a polishing head on the end. The 2 wheels at the center are used for grinding and shaping your piece. The expandable drum then gives you the ability to pre-polish and ready the piece for the final polish.

The polishing head comes with a leather disc attached, which is a universal polishing disc for working with stones. This disc can be changed out easily for pieces that require the friction of felt or if you prefer to polish using diamond discs.

Cabbing Machines

Cabbing Machines are machines specially built for making cabochons. Barranca Diamond has several Cab Makers in both 6" and 8" versions and either diamond or silicon carbide versions. The GP6 models come in Silicon Carbide, Diamond and a Wheels & Pads model. The GP6-6 is a six wheel machine that gives you lots of versatility and the GP8 Super Cab Maker uses 8" wheels and comes with a long list of accessories.

The Cab King 6" and 8" machines are excellent for making cabochons. These 8-station grinder/polishers come with a full list of accessories. They are built on a sturdy base board and have aluminum splash hoods with adjustable clear splash shields, plastic pans with drain holes, side splash guards, and metal hand rests. Both sizes also have optional Trim Saw Attachments.


For the truly do-it-yourself types, we have Covington arbors that are suitable for a variety of needs and purposes. These simple 2-station arbors are fully customizable. They do not come with a motor or base board. Instead these units are designed to build yourself and place into any available location in a workshop. These arbors come with a mild steel shaft, a fixed flange, a floating flange, and a nut on either side.

The first main difference between the open and the closed arbor is the height and the size of the wheel that it can hold. The Open Arbor can hold larger wheels with a small shim to raise the unit up. Secondly the open arbor has an exposed pulley and v-belt while the Closed Arbor has a fully enclosed front pulley and arbor. Additionally, the open arbors come with a longer shaft.

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